The present invention concerns a method of assembling hubs.
Propeller hubs for boat engines usually consist of a propeller sleeve on which are mounted the propeller blades, a hub sleeve which is arranged coaxially with the propeller sleeve and in which is insertable the propeller shaft, and a rubber bushing positioned between the propeller sleeve and the hub sleeve, said rubber bushing being arranged to absorb torsional stresses and, on account of its elasticity, to protect the propeller and power transmission means, particularly from the stresses occuring from heavy thrusts as may occur for various reasons.
In assemblying a hub unit of this kind certain problems have hitherto presented themselves on account of the inappropriate way in which the task has been performed. Initially, the rubber bushing was secured to the hub sleeve through vulcanization. Then, the bushing together with the hub sleeve were forced into the propeller sleeve while compressing the bushing radially, and in its compressed state, as desired, the bushing contacted the inner surface of the propeller sleeve with considerable friction.
This method is inadvantageous in that specialty tools are required to perform the assembly and considerable force necessary to urge the bushing into the propeller sleeve. In order to be able to withstand the stresses exerted on it during this work, the propeller sleeve in addition had to have a considerable material thickness. Since the bushing in its compressed state, as mentioned, offers large friction against the propeller sleeve, it was furthermore difficult to orientate the hub sleeve and the bushing correctly in the propeller sleeve.